Proxy settings via environment variables can interfere with this
test. The requests library will automatically pick up proxy
settings from environment variables. Proxy settings can force the
local connection over the proxy, which might not support that,
then this fails with an error like 405 or others.
There is no longer any reason for these to be intertwined.
This deliberately avoids touching some files as much as possible because
they are super tangled and due to be replaced. Those files are:
* fdroidserver/build.py
* fdroidserver/update.py
# Conflicts:
# tests/testcommon.py
# Conflicts:
# fdroidserver/btlog.py
# fdroidserver/import_subcommand.py
The existing logic from d1ddd525c in !1225 is confusing because it adds its
own retry loop on top of the retry mechanism that is built into requests.
So this test confirms that setting `download_file(retries=3)` actually
results in more than three retries.
